A virtualization method called “paravirtualization” is known from publication XEN 2002, University of CAMBRIDGE, Technical Report UCAM-CL-TR-553. This method uses modifications of OS source code to be virtualized to replace privileged instructions with calls for equivalent services supplier by a hypervisor. The hypervisor is run in the most privileged mode of the processor, while the virtualized OS are run in a less privileged mode than that of the hypervisor, and the processes managed by the virtualized OS are run in a less privileged mode than that of the OS. This is why this method can only be implemented on processors having at least three different privilege levels.